Ischemic heart disease causes mitral regurgitation by the combination of ischemic dysfunction of the papillary muscles, and the dilatation of the left ventricle that is present in ischemic heart disease, with the subsequent displacement of the papillary muscles and the dilatation of the mitral valve annulus.
Dilation of the annulus of the mitral valve prevents the valve leaflets from fully coapting when the valve is closed. Mitral regurgitation of blood from the left ventricle into the left atrium results in increased total stroke volume and decreased cardiac output, and ultimate weakening of the left ventricle secondary to a volume overload and a pressure overload of the left atrium.
Chronic or acute left ventricular dilatation can lead to papillary muscle displacement with increased leaflet tethering due to tension on chordae tendineae, as well as annular dilatation.
U.S. Pat. No. 7,431,692 to Zollinger et al. describes an adjustable support pad for adjustably holding a tensioning line used to apply tension to a body organ. The adjustable support pad can include a locking mechanism for preventing slidable movement of the tensioning element in one or both directions. The locking mechanism may include spring-loaded locks, rotatable cam-like structures, and/or rotatable spool structures. The adjustable support pad may be formed from rigid, semi-rigid, and/or flexible materials, and may be formed to conform to the outer surface of a body organ. The adjustable support pad can be configured to adjustably hold one or more separate tensioning lines, and to provide for independent adjustment of one or more tensioning lines or groups thereof.
US Patent Application Publication 2007/0118151 to Davidson describes a method and system to achieve leaflet coaptation in a cardiac valve percutaneously by creation of neochordae to prolapsing valve segments. This technique is especially useful in cases of ruptured chordae, but may be utilized in any segment of prolapsing leaflet. The technique described herein has the additional advantage of being adjustable in the beating heart. This allows tailoring of leaflet coaptation height under various loading conditions using image-guidance, such as echocardiography. This offers an additional distinct advantage over conventional open-surgery placement of artificial chordae. In traditional open surgical valve repair, chord length must be estimated in the arrested heart and may or may not be correct once the patient is weaned from cardiopulmonary bypass. The technique described below also allows for placement of multiple artificial chordae, as dictated by the patient's pathophysiology.
The following patents and patent application publications, relevant portions of which are incorporated herein by reference, may be of interest:    PCT Patent Application Publication WO 07/136783 to Cartledge et al.    U.S. Pat. No. 5,306,296 to Wright et al.    U.S. Pat. No. 6,569,198 to Wilson et al.    U.S. Pat. No. 6,619,291 to Hlavka et al.    U.S. Pat. No. 6,764,510 to Vidlund et al.    U.S. Pat. No. 7,004,176 to Lau    U.S. Pat. No. 7,101,395 to Tremulis et al.    U.S. Pat. No. 7,175,660 to Cartledge et al.    US Patent Application Publication 2003/0050693 to Quijano et al    US Patent Application Publication 2003/0167062 to Gambale et al.    US Patent Application Publication 2004/0024451 to Johnson et al.    US Patent Application Publication 2004/0148021 to Cartledge et al.    US Patent Application Publication 2004/0236419 to Milo    US Patent Application Publication 2005/0171601 to Cosgrove et al.    US Patent Application Publication 2005/0288781 to Moaddeb et al.    US Patent Application Publication 2007/0016287 to Cartledge et al.    US Patent Application Publication 2007/0080188 to Spence et al.
The following articles, which are incorporated herein by reference, may be of interest:    O'Reilly S et al., “Heart valve surgery pushes the envelope,” Medtech Insight 8(3): 73, 99-108 (2006)    Dieter R S, “Percutaneous valve repair: Update on mitral regurgitation and endovascular approaches to the mitral valve,” Applications in Imaging, Cardiac Interventions, Supported by an educational grant from Amersham Health pp. 11-14 (2003)